^•HfOBHB 

TK 


HOW  TO  BUILD 


-FOURTH  POWER 


UC-NRLF 


77h 


UNIVERSITY  OF  CALIFORNIA 

ANDREW 

SMITH 

HALLIDIE: 


HOW  TO  BUILD 


A   OjSfE-FOUKTH   HORSE   POWER 


MOTOR^DYNAMO 


By  A.    E.  WATSON. 


ILLUSTRATED    WITH   WORKING    DRAWINGS. 


LYNN,  MASS.  : 

BUBIER    PUBLISHING   COMPANY. 
1894. 


COPYRIGHTED    1894. 
RUBIER     PUBLISHING     CO. 

LYNN,   MASS. 


HOW  TO  BUILD 

A  ONE-FOURTH  HORSE  POWER  MOTOR  OR  DYNAMO. 


NO  less  accurate  workmanship  is  required  in  the  construction 
of  a  small  dynamo  than  in  one  of  a  larger  size.  However, 
in  this  chapter  is  described  a  machine  of  such  size  and 
arrangement  of  parts  as  to  be  within  the  reach  of  amateurs' 
tools,  yet  capable  of  continuous  and  efficient  service.  It  can  be 
used  as  dynamo  or  motor,  series,  shunt,  or  compound  wound, 
for  any  potential  not  exceeding  1  10  volts.  Figures  i  and  2 
show  the  complete  machine  in  side  and  end  elevations. 

For   convenience    the    description    will    be    divided    as   follows  : 

1.  Field    magnet   and    frame. 

2.  Armature,    shaft,     and    pulley. 

3.  Bearings. 

4.  Commutator. 

5.  Brushes,    holders    and    yoke. 

6.  Winding. 

7.  Connections. 

8.  Testing   and    using. 

The  Field  Magnet  and  Frame  consists  of  two  cast  iron  "pole 
pieces"  united  by  a  wrought  iron  "core."  Referring  to  Figure  3~(b), 
it  will  be  seen  that  the  castings  are  apparently  alike,  but  the 
patterns  must  be  so  made  that  the  arms  for  supporting  the 


M       M     V~l  f\ 


4 

bearings  will  come  on  reverse  sides,  so  that  when  the  two  are 
placed  facing  each  other,  both  long  arms  will  be  on  the  com- 
mutator side  and  both  short  arms  on  the  pulley  side. 

Provided  with  the  castings,  the  holes  for  the  core  should 
be  bored  out  smoothly  to  two  inches  in  diameter.  For  doing  this 
the  castings  may  be  either  bolted  to  the  traveling  carriage  of  a 
lathe,  and  a  boring  bar  inserted,  or  to  a  face  plate,  using 
a  rigid  inside  boring  tool.  If  possible  finish  with  a  reamer. 
Drill,  tap  and  counter-bore  for  the  seven-sixteenths  inch  screw 
"a"  on  the  bolt  and  screw  list,  Figure  4.  The  slots  at  the 
bottom,  which  may  well  have  been  cored  part  way,  can  now 
be  extended  through  with  a  hack  saw.  The  core  is  to  be  of 
wrought  iron,  seven  and  three-sixteenths  inches  long,  smoothly  turned 
to  two  inches  in  diameter.  If  what  commonly  known  as  "cold 
rolled"  steel  is  available,  no  turning  will  be  necessary.  This 
quality  of  steel  is  very  soft  and  quite  as  good  as  wrought  iron 
for  magnetic  purposes. 

Put  one  pole  piece  on  the  core,  tighten  the  clamping 
screw ;  drill  a  one-fourth  inch  hole  through  the  cast-iron  into  the 
steel  and  drive  in  a  steel  pin  about  three-fourths  inch  long. 
These  two  parts  will  then  be  permanently  attached.  Slip  on  the 
other  pole  piece,  see  that  the  protruding  arms  are  parallel, 
tighten  in  place,  and  drill  a  one-fourth  inch  hole  in  the  end, 
so  as  to  be  half  in  the  core  and  half  in  the  pole  piece,  in  the 
location  as  shown,  and  drive  in  another  pin.  This  method 
locates  the  two  parts  definitely,  but  allows  easy  removal  of  one 
pole  piece  for  placing  the  field  spool. 

The  boring  of  the  ends  of  the  arms  and  the  field  may 
now  be  done.  Bolt  the  structure  as  now  assembled  to  the  car- 
riage of  a  screw  cutting  lathe.  With  a  boring  bar  between 


centers,  take  first  a  slight  chip,  at  slow  feed.  If  carefully  done, 
there  will  be  no  danger  of  breaking  off  the  arms,  but  if  "con- 
venient some  sort  of  supports  can  be  devised  to  brace  the  long 
ones.  The  finished  diameter  should  be  three  and  one-sixteenths 
inches.  Drill  and  counterbore  the  holes  in  the  arms  for  screws 
"b"  ;  drill  and  tap  the  two  in  the  top  for  screws  "c"  ;  drill  the 
four  in  the  feet  for  screws  "d".  The  removal  of  sharp  corners 


T 


FIGURE    4. 

or    fins    on   the    castings    will    complete    the    machine    work    on    the 
field    magnet. 

Armature,  Shaft  and  Pulley.  The  armature  is  of  the 
toothed  drum  type,  built  up  of  laminations  of  sheet  iron.  Fig- 
ure 5,  #,  shows  one  of  these  sheets.  If  punchings  of  this  description 
canuot  be  otherwise  obtained,  the  builder  may  proceed  as  follows  : 
From  stove  pipe  iron  cut  three  and  one-eighth  inch  squares. 
Enough  should  be  cut  to  make  a  thickness  two  and  one-fourth 


9 

inches  when  tightly  clamped  together.  Cut  the  corners  so  as  to 
make  the  sheets  octagonal.  Clamp  them  between  plates  of  one- 
fourth  or  three-eighths  inch  iron  and  drill  a  five-eighths  inch 
hole  as  near  the  center  as  possible.  Put  in  a  short  five-eighths 
inch  turned  bolt  and  screw  on  the  nut.  Remove  the  other 
clamps  and  turn  the  mass  to  a  diameter  of  three  inches. 
Without  disturbing  the  center  bolt,  put  the  cylinder  thus 
formed  in  a  milling  machine  or  gear  cutter  and  saw  out  the 
'the  sixteen  slots  as  shown,  one-fourth  inch  wide  and  three-eighths 
deep. 

Part  of  the  work  on  the  shaft  may  now  be  done.  Procure 
a  suitable  length  of  cold  rolled  steel,  five-eighths  inch  in  diam- 
eter, center  it  in  a  lathe,  with  the  aid  of  a  back  rest,  and  turn 
it,  excepting  the  space  three  inches  long  in  the  centre,  to  nine- 
sixteenths  inch  in  diameter.  On  the  ends  of  that  space  cut  27 
threads  per  inch  for  a  distance  of  three-eighths  inch.  Cast-iron 
flanges  or  "  heads,"  for  screwing  on  these  threaded  portions,  are 
clearly  shown  at  '4  <$,"  Figure  5.  Screw  one  of  these  tightly 
in  place  and  slip  on  the  punchings.  It  will  be  necessary  to  put 
a  piece  of  iron  or  brass  one-fourth  inch  thick  and  about  three 
inches  long  in  one  of  the  grooves  in  the  sheets,  to  keep  the 
teeth  matched.  With  this  bar  still  in  place,  tightly  screw 
on  the  other  head,  using  a  spanner  wrench  with  pins  en- 
gaging in  the  two  small  holes  as  shown.  By  oiling  its 
surface  and  threads,  this  may  be  easily  done  without  allowing 
the  sheets  to  slide  on  each  other.  Replacing  the  armature  in 
the  lathe,  it  will  probably  be  found  that  the  shaft  does  not 
run  true ;  this  is  due  to  the  fact  that  sheet  iron  cannot  be 
procured  of  an  exactly  uniform  thickness,  and  the  shaft  has 
had  to  bend  to  compensate  for  the  difference.  With  a  lever 


10 


1 1 


spring   the    shaft    until    it    runs     true,     and     complete     the     turning 
to    the    required    dimensions.       Leave     the     portions     for     the    bear- 


FIGURE    6. 

ings    about     one-hundredth     inch  large    to    allow    for    final    fitting. 
Put    in    the    small    pin    for    holding     the     commutator     in     position. 


12 

After  turning  and  fitting  the  pulley,  a  No.  30  drill  may  be 
run  in  on  the  end,  half  in  the  pulley  and  half  in  the  shaft. 
Use  a  piece  of  one-eighth  inch  steel  wire  for  a  key  and  so 
locate  the  set  screw  as  to  hold  the  key  in.  Figure  5  shows 
the  completed  structure. 

Bearings.  In  order  that  magnetism  may  not  be  diverted 
from  its  useful  path,  the  bearings  should  be  of  brass,  or 
some  similar  material.  The  construction  of  these  is  given  in 
Figure  6.  For  the  pulley  end  a  longer  bearing  is  provided 
than  for  the  commutator  end,  and  the  center  so  located  as  to 
carry  the  pulley  at  a  safe  distance  from  the  ends  of  the  arms. 
Proximity  would  encourage  leakage  of  magnetism. 

Chuck  the  castings,  bore  out  the  cored  holes,  and  ream 
to  three-fourths  inch  in  diameter.  Mount  them  on  an  arbor  and 
turn  the  ends  to  three  and  one-sixteenths  inches  in  diameter 
and  on  the  commutator  end  casting  cut  the  straight  portion 
for  the  yoke  bearing  one  inch  in  diameter  for  a  distance  of 
one-fourth  inch.  Lay  on  the  oil-well  covers  and  drill  for  the  pins 
on  which  they  hinge.  Set  the  bearings  in  position  between 
the  ends  of  the  arms ;  it  will  ensure  their  alignment  if  a 
three-fourths  inch  arbor  is  inserted,  long  enough  to  extend  through 
both.  A  one-fourth  inch  drill  may  be  run  through  the  pre- 
viously drilled  holes  in  the  arms  for  about  one-eighth  inch  into 
the  brasses.  Drill  one-half  inch  further  with  a  No.  8  drill  and 
tap  out  14-20.  The  screws  "b"  may  now  be  inserted  and  arbor 
removed. 

Quite  a  variety  of  materials  are  suitable  for  the  bushings 
or  "linings"  for  the  bearings.  Brass,  gun  metal,  graphite, 
cast  iron,  babbitt  metal  and  lignum  vitae  are  used.  Gun  metal 
is  in  good  favor.  Drill  out  the  castings,  ream  them  to  one- 


half  inch  in  diameter,  mount  them  on  an  arbor,  turn  the  out- 
side and  ends  to  size.  The  oil  groove  may  be  cut  with  a 
round-nosed  hand  tool.  It  will  be  noticed  that  the  linings  are 


FIGURE       7. 

shorter  than  the  castings  into  which  they  are  to  be  forced. 
The  purpose  is  to  provide  a  surface  for  catching  the  oil  that 
may  be  thrown  from  the  shaft  while  running.  Locate  the 
linings  so  as  to  bring  the  armature  in  center  of  the  field,  and 


H 

allow  about  one-sixteenth  inch  for  end  motion ;  then  drill 
through  the  bottom  of  the  oil-wells  and  insert  short  pieces  of 
brass  tube.  When  occasion  requires  the  removal  of  the  bushings, 
these  tubes  may  be  driven  entirely  through  and  out  of  the  way. 

Thick  grease  of  about  the  consistency  of  lard  is  to  be  used 
for  lubrication,  and  a  little  \vill  last  a  long  time.  The  warmth 
of  the  bearing  will  •  melt  just  enough  grease  to  ensure  proper 
oiling. 

Commutator,  The  construction  of  a  commutator  is  often 
a  Waterloo  to  an  amateur,  but  the  one  here  described  is 
compact,  durable  and  well  insulated.  A  comparatively  small 
lathe  and  easily  obtained  materials  will  suffice  for  its  construc- 
tion. There  are  sixteen  divisions,  or  "segments,"  made  of  smooth 
copper,  drawn  wedge-shaped,  or  of  filed  castings  to  fit  around 
into  a  complete  circle ;  or  a  ring  may  be  turned  to  the  right 
size  and  then  split  into  sixteen  parts.  The  latter  may  be  the 
more  available  method. 

Procure  a  piece  of  copper  tube,  or  gun  metal  casting,  that 
in  the  rough  measures  about  one  and  seven-eighths  inches 
outside  diameter,  fifteen-sixteenths  inch  inside,  and  seven-eighths 
inch  long.  Bore  out  the  inside  to  one  inch  in  diameter,  mount 
it  on  an  arbor  and  turn  the  outside  to  the  dimensions  shown 
at  "a"  in  Figure  7.  While  still  on  the  arbor,  place  it  in  a 
milling  machine,  slotter,  or  gear  cutter,  and  saw  it  into  six- 
teen segments.  Let  the  saw  be  thin  and  cut  within  one-thirty- 
second  inch  of  the  arbor.  Fit  strips  of  mica  to  the  saw  cuts, 
then  finish  cutting  the  segments  apart.  File  off  the  burrs  and 
assemble  the  segments  and  insulations  into  a  circle.  Secure  them 
with  a  string  or  rubber  band,  and  prepare  the  rest  of  the 
structure. 


i6 

A  piece  of  seamless  brass  tube,  one  and  three-eighths  inches 
long,  three-fourths  inch  outside  and  nine-sixteenths  inch  inside 
diameter  is  to  be  threaded  for  a  short  distance  at  each  end. 
Use  a  fairly  fine  thread,  say  twenty  to  the  inch.  File  a  slot 
one-eighth  inch  wide  in  one  end  to  fit  the  pin  that  was  located 
in  the  shaft.  Tap  two  iron  or  brass  nuts  to  match.  Drill  two 
holes  in  these  thin  nuts  to  allow  the  use  of  a  spanner  wrench. 
Screw  one  of  these  on  tightly.  Turn  two  vulcanized  fiber  discs 
as  shown  at  "b"  in  Figure  7,  and  slide  one  on  the  brass 
tube ;  set  the  segments  into  the  grove ;  put  on  the  other  disc, 
and  screw  on  the  other  nut,  but  be  careful  not  to  let  the  seg- 
ments get  "skewed"  or  strained  into  a  spiral. 

Provision  must  now  be  made  for  getting  electrical  connec- 
tion between  the  segments  and  the  wires  that  are  to  be  wound 
on  the  armature.  Insert  an  arbor  in  the  commutator  and  tilt  it 
on  a  wooden  jig  or  frame  to  an  angle  of  about  15  degrees. 
Prick-punch  into  the  fiber  in  sixteen  places  opposite  the  centers 
of  the  segments,  and  drill  through  the  fiber  with  a  No.  32 
drill ;  then  continue  through  the  segment  with  a  No.  40  drill, 
and  thread  with  a  4-36  tap.  Brass  rods,  threaded  4-36,  "e'' 
Figure  4  may  be  screwed  into  these  holes,  care  being  taken 
not  to  let  them  extend  through  the  segments  and  touch  the 
tube.  Bind  some  copper  wire  tightly  around  the  segments  to 
hold  them  in  place,  and  remove  the  nut  from  the  end  farthest 
from  the  connection  screws ;  take  off  the  disc  and  clean  out 
the  chips  of  copper  that  may  have  collected.  Reassemble  the 
parts,  remove  the  binding  wire,  and  turn  the  surface  of  the  seg- 
ments even,  finishing  with  a  piece  of  fine  sand  paper. 

Brushes,  Holders  and  Yokes.  Two  kinds  of  brushes  are 
commonly  used,  copper  and  carbon,  with  appropriate  holders. 


The  same  supports  called  "yoke  and  studs"  will  fit  either.  For 
the  former,  "planished"  or  hard  rolled  leaf  copper  about  five- 
one-thousandths  inch  thick  is  to  be  cut  in  strips  seven-sixteenths  inch 


FIGURE    9. 

wide  and  two  inches  long.  Enough  to  equal  one-eighth  inch 
thickness  should  be  grouped  together  and  soldered  at  one  end, 
the  other  bevelled  to  an  angle  of  45  degrees,  to  fit  the  commu- 
tator. The  holder  is  shown  assembled  and  in  detail  in  Fig- 


ure  8.  There  are  two  brass  castings,  a  body,  "a"  and  shoe 
"b"  ;  a  clamp  "c"  of  sheet  copper,  and  thumb  screw  "d"  of 
brass.  The  construction  is  such  that  the  pressure  of  the  screw 
binds  both  the  brush  and  the  holder  securely.  A  slight  loosen- 
ing of  the  screw  will  allow  the  holder  to  be  tilted,  and  remove 
the  brush  from  the  commutator,  without  changing  the  adjustment. 

A  suitable  carbon  brush  holder  is  given  in  Figure  9.  The 
brass  body  casting  "a"  is  drilled  at  one  end  one-fourth  inch  in 
diameter,  the  same  as  the  copper  holder,  but  the  other  end  is 
drilled  seven-sixteenths  of  an  inch.  A  presser  "b"  is  made  of 
steel  or  brass  wire  about  five  one-hundreclths  inch  in  diameter. 
The  clamp  "c"  is  also  a  casting,  and  serves  to  retain  the  short 
end  of  the  spring.  By  turning  the  clamp  one  way  or  the  other 
a  variation  of  tension  on  the  spring  may  be  obtained,  and  the 
screw  binds  it  and  the  holder  in  any  desired  position  on  the 
stud.  The  brush  is  itself  a  short  piece  of  standard  electric 
light  carbon,  with  one  end  filed  to  fit  the  commutator  the 
other  with  a  groove  for  keeping  the  presser  in  place. 

Make  the  brush  holder  "studs"  of  one- fourth  inch  brass 
rod.  See  "a"  Figure  10.  One  end  is  turned  to  three-sixteenths 
inch  diameter  and  threaded  10-24.  For  the  flange,  a  brass 
washer  may  be  slipped  on  the  three-sixteenths  inch  portion, 
soldered  and  turned  true.  "b"  and  "f"  are  brass,  the  washers 
"c"  and  bushing  "d"  are  hard  rubber;  terminal  clip  "e"  is 
sheet  copper. 

It  is  necessary  to  provide  some  means  of  adjusting  the  posi- 
tion of  the  brushes.  This  is  accomplished  by  attaching  the 
studs  to  a  rocker  or  "yoke."  The  construction  is  shown  also 
in  Figure  10.  Bore  out  the  center  of  the  casting  to  fit  on  the 
turned  portion  of  the  bearing  as  previously  noted ;  drill  and  tap 


FIGURE    IO. 


20 

for  the  thumb  screw,  and  then  saw  the  slot.  The  rounding 
ends  should  be  finished  so  as  to  allow  the  studs  to  be  firmly 
held  and  kept  parallel  with  each  other. 

Winding-.  Having  completed  the  general  mechanical 
parts  of  the  machine,  the  builder  will  be  ready  for  the  more 
purely  electrical.  Preliminary  to  the  placing  of  the  wire,  there 
must  be  the  uninteresting  work  of  suitably  insulating  the  core. 
An  amateur  is  liable  to  slight  this  part  of  the  work. 

The  winding  easily  divides  itself  into  the  two  separate  por- 
tions,— armature  and  field.  Just  what  sizes  of  wire  to  use 
w^ill  depend  on  the  voltage  and  current  desired,  but  the  same 
general  directions  will  answer  for  all.  As  the  running  of 
incandescent  lamps  is  a  common  application  of  even  small 
dynamos,  a  winding  for  lighting  three  standard  50  volt  lamps 
will  be  explained  in  detail,  and  sizes  stated  for  various  other 
potentials. 

First,  insulate  the  core ;  sharp  corners  are  to  be  filed  off, 
and  a  thin  coat  of  shellac  put  on,  extending  along  the  shaft  also  for 
one  and  one-half  inches.  Wind  several  turns  of  thin,  tough 
brown  paper  around  the  shaft,  gash  the  paper  a  little  so  that 
it  will  lap  up  on  the  heads  for  one-eighth  inch.  Cut  a  num- 
ber of  discs  of  paper  three  and  one-eighth  inches  in  diameter 
with  five-eighths  inch  hole,  and  some  strips  two  and  one-half 
inches  wide  of  indefinite  length.  Slip  on  a  disc  over  each 
head  and  shellac  it  on.  When  dry  make  a  single  radial  cut 
between  the  teeth  with  a  pair  of  scissors  and  turn  the  edges  of 
the  paper  over  the  corners  into  the  grooves.  Start  the  strip  of  paper  in 
the  bottom  of  a  groove,  and  pass  it  over  a  tooth  into  the  next 
groove ;  press  it  well  into  the  corners  with  a  thin  strip  of 
wood,  and  then  press  it  down  into  the  next  groove,  and  so  on 


21 


22 

around  the  core  to  the  starting  place ;  cut  the  paper,  but  do  not 
lap  the  ends.  Slit  the  overhanging  edges  and  bend  them  so  as 
to  cover  any  exposed  iron.  Put  another  disc  on  the  heads, 
slit  and  bend  over  their  edges  as  before ;  put  another  strip  all  the 
way  around  the  core,  in  the  grooves,  but  be  careful  to  have  the 
joints  always  in  different  places  in  successive  layers.  Four  layers 
everywhere  will  be  a  sufficient  amount.  The  paper  should  occupy 
only  so  much  space  that  a  three-sixteenths  inch  strip  can  be 
forced  down  into  the  insulated  grooves.  Use  thin  shellac  freely 
as  an  adhesive  and  do  not  allow  the  paper  to  "pucker" 
anywhere. 

Provide  a  continuous  coil  of  about  one  and  three-fourths 
pound  No.  22  (twenty-five  one-thousandths  inch  in  diameter) 
double  cotton  covered  magnet  wire.  Rest  the  armature  between 
lathe  centers  or  on  other  convenient  support,  so  as  to  be  turned 
back  and  forth  as  the  winding  progresses.  Lay  the  starting 
end  of  the  wire  through  one  of  the  grooves  toward  the  commu- 
tator end.  For  the  moment  it  may  be  twisted  around  the  end 
of  the  shaft.  Carry  the  continuation  of  the  wire  across  the 
head  at  the  pulley  end,  giving  the  core  a  half  turn  so  as  to 
bring  the  opposite  groove  on  top ;  lay  the  wire  in  this  groove 
but  leave  enough  room  in  passing  the  shaft  to  allow  for  five 
more  turns.  Cross  the  head  at  the  commutator  end,  at  the 
same  distance  from  the  shaft  back  to  the  starting  point,  rotating 
the  core  back  to  its  original  position.  Lay  a  second  turn 
beside  the  first,  then  a  third,  and  so  on  until  six  turns  are  on. 
This  should  make  just  one  layer  in  the  grooves.  The  wires 
may  be  smoothed  down  and  firmly  pressed  into  position  with 
the  aid  of  a  chisel-shaped  piece  of  soft  wood.  If  the  wires 
bulge  a  little  in  the  grooves,  pull  them  further  away  from  the 


shaft,  thus     drawing     them    tight    in    other    places.      If     sufficient 

room  has    not    been     allowed    to    get    all    the    turns     in     past    the 

shaft,  a    little  stretching  of  this    kind    may  provide  space.       Shellac 

these  six    turns    and    let    them    dry.        "A",  Figure    u,   show7s    this 


llo  Volts.    A. 


SO  Volts,    B 


ZSVolts.    C. 


7  Volts.    D. 


FIGURE    12. 

first  layer.  Continue  the  winding  in  a  second  layer,  and  place 
six  turns  on  the  other  side  of  the  shaft.  tlB",  Figure  n, 
shows  this  stage.  Shellac  again  and  when  dry,  wind  on  a 
third  layer  of  six  turns,  passing  the  shaft  on  the  same  side 


34 

as  the  first  layer,  only  further  out.  See  k'C"  Figure  n.  A 
fourth  layer  goes  on  the  other  side,  as  shown  in  "D",  and  also 
a  half  layer  of  three  turns, — "E".  Make  a  loop  in  the  wire 
about  three  inches  long,  twist  the  two  together  and  lay  the 
continuation  in  the  groove  next  to  the  starting  point.  There 
will  now  be  two  slots  a  little  less  than  half  full  of  wire,  and  the 
twenty-seven  turns  will  be  so  spread  over  the  ends  of  the 
armature  as  to  be  but  one  layer  deep  where  they  pass  the 
shaft.  Wind  twenty-seven  turns  in  the  next  slot  and  its  op- 
posite. These  wires  will  cross  the  first  wire  at  a  slight  angle ; 
bring  out  a  second  loop  and  wind  twenty-seven  turns  in  the 
third  slot  and  its  opposite,  and  so  on  around  until  each  of 
the  slots  have  twenty-seven  wrires  in  them  and  eight  loops  are 
made  for  connecting  to  the  commutator.  Continue  a  ninth 
coil  of  twenty-seven  turns  on  top  the  first  coil ;  bring  out  a  ninth 
loop,  and  wind  a  tenth  coil  of  twenty-seven  turns  on  top  the 
second  coil,  and  so  on  until  the  sixteen  grooves  have  fifty-four 
wires  each  and  fifteen  loops  are  protruding.  Cut  the  wire  and 
twist  it  to  the  starting  end.  This  will  give  a  sixteenth  loop. 
No  cut  is  to  be  made  during  the  entire  winding  up  to  this 
point.  Trim  off  all  superfluous  insulation  on  the  shaft  and  slip 
the  commutator  into  position.  Remove  the  cotton  covering  from 
the  portions  of  the  loops  next  to  the  screws  in  the  segments. 
Insert  both  wires  of  one  of  the  loops  in  the  slot  in  one  of  the 
screws ;  this  connection  should  not  be  in  a  direct  axial  line,  but 
carried  to  the  second  segment  beyond,  in  the  direction  of  rota- 
tion. See  "F",  Figure  IT.  Solder  the  wires  in  position. 
Bring  the  second  loop  to  the  next  segment,  and  so  on  until  all 
have  been  connected.  The  appearance  will  then  be  as  if  the 
commutator  had  been  given  one-eighth  of  a  turn  after  the  wires 


25 

had  been  connected.  The  object  of  this  advance,  or  "lead",  is 
to  bring  the  brushes  in  a  more  convenient  position.  Shellac  the 
connecting  wires  to  prevent  unravelling  of  the  insulation. 
Remove  the  paper  from  the  surface  of  core  so  that  the  ends 
of  the  sheet  iron  teeth  will  be  exposed.  If  the  winding  has 
been  carefully  done  and  tightly  pressed  in  place,  no  binding 
wires  will  be  needed ;  but  if  desired,  a  place  about  one-half  inch 


FIGURE   1 3 . 

wide  may  previously  have  been  turned  in  the  center  of  the 
core  to  a  diameter  of  two  and  fifteen-sixteenths  inches ;  strips 
of  thin  mica  may  be  laid  over  the  copper  wires  for  extra  in- 
sulation, and  this  space  tightly  wound  with  fine  brass  wire. 
Solder  the  wires  together  before  loosening  the  tension. 

It  is  common  practice  among  manufacturers  of  dynamos  and 
motors  to  cover  the  exposed  ends  of  the  armature  with  conical 
"dressings"  of  canvas.  The  amateur  may  not  feel  inclined  to 
bother  with  this. 


26 


Other  windings  may  be  :  —  Seven  volts,  suitable  for  plating,  can 
be  obtained  by  using  No.  13  (seventy-two  one-thousandths  inch  di- 
ameter) wire.  Two  turns  will  make  one  layer,  and  two  layers 
put  in  each  slot  for  each  half  winding,  and  loops  brought  out  as 
usual  and  four  turns  wound  in  the  next  slot.  "D"  Figure  12 


3~ 


~  X 

1 


-,i 


£f' 


FIGURE     14. 

shows  the  eight  wires,  the  blackened  ones  representing  the  four 
turns  of  the  first  half-winding,  the  light  ones  showing  the  wires 
of  the  last  half.  This  wire  will  allow  an  output  of  thirty  am- 
peres, and  copper  brushes  of  extra  thickness  should  be  used. 

Twenty-five  volts.     This  is  a  suitable  potential  for  a  motor  using 
batteries    for    a    source    of    current.        Use    No.     17    wire     (forty-five 


27 

one-thousandths  inch  diameter).  Put  four  turns  per  layer,  three  layers 
deep  for  each  half-winding.  See  "C"  Figure  12.  It  may  be  neces- 
sary to  use  slightly  thinner  insulation  in  the  slots  in  order  to 
get  the  wire  in,  but  the  potential  is  so  low  that  there  would 
be  no  danger  of  "ground"  or  "short  circuit."  In  crossing  the 
heads,  let  six  wires  be  on  one  side  of  the  shaft,  and  three  on 
the  other,  in  regular  order.  The  halves  of  the  winding  will 
then  balance  the  inequality.  This  winding  will  allow  a  cur- 
rent of  eight  amperes. 

One  hundred  and  ten  volts.  It  is  practicable  to  wind  an  arm- 
ature for  this  potential,  but  special  care  and  considerable  patience  will 
be  required.  No.  26  wire  (sixteen  one-thousandths  inch  diameter)  is 
wanted.  Wind  six  and  one-half  layers,  eight  turns  per  layer  for 
each  half  winding.  "A",  Figure  12,  shows  the  arrangement  in 
one  slot.  There  will  be  52  turns  per  segment.  The  current 
capacity  will  be  two  amperes. 

Higher  voltage  should  not  be  attempted  in  so  small  a  ma- 
chine, as  the  excessive  number  of  turns  of  wire  introduces 
the  insulation  so  many  times  as  to  reduce  the  amount  of  copper 
below  its  safe  current-carrying  capacity.  An  armature  would 
last  so  short  a  time  as  scarcely  to  repay  the  builder  for  his 
trouble. 

Field  Winding.  In  consequence  of  the  round  core  of  the 
field  magnet,  this  winding  can  be  quickly  done  in  a  lathe. 
Figure  13  shows  a  detail  of  a  spool.  It  consists  of  three  leatheroid  or 
fiber  discs  four  inches  outside  diameter,  the  two  outer  ones  having 
a  hole  two  and  one-sixteenth  inches  diameter,  the  inner  one 
two  and  one-eighth  inches.  A  tin  or  other  thin  sheet  metal 
tube,  soldered  along  its  lapped  edge,  and  rolled  with  a  small 
flange  at  the  ends,  holds  the  discs  in  position.  For  winding, 


28 

the  spool  may  be  slipped  on  a  wooden  arbor  with  check-pieces 
or  flanges  to  keep  the  discs  from  spreading  by  the  crowding- 
action  of  the  wire. 

Wind  four  or  five  layers  of  paper  around  the  tin  tube,  duly 
shellacked.  The  edges  of  the  paper  can  be  pressed  under  the 
loose  disc  and  lapped  onto  the  others.  Put  the  starting  end  of 
the  wire  through  the  notch,  and  draw  through  a  considerable 
length  depending  on  the  size  used.  Wind  one  turn  of  this  end 
length  backwards  around  the  spool  and  coil  the  rest  around  the 
arbor.  Press  the  loose  disc  against  this  one  turn,  and  wind  two 
or  three  layers  in  the  main  part  of  the  spool.  By  hand,  wind 
two  or  three  turns  backwards,  from  the  wire  on  the  arbor. 
Put  a  piece  of  thin  paper  on  the  main  coil  and  wind  several 
more  layers ;  give  the  end  wire  a  few  more  turns  and  so  on 
until  the  requisite  number  is  in  place.  It  will  be  seen  that 
the  object  of  the  extra  disc  and  the  long  protruding  end  at  the 
start  was  to  keep  the  wire  leading  to  the  first  layer  well  insu- 
lated from  the  successive  ones,  and  also  to  leave  the  inside  end 
so  that  if  accidentally  broken  off,  a  turn  or  two  can  be  un- 
wound without  disturbing  the  main  part  of  the  spool. 

If  fine  wire  is  used  the  ends  may  finally  be  led  through 
holes  drilled  near  the  edges  of  the  discs,  but  large  wires  can 
be  tied  to  the  discs  by  string  taken  through  a  number  of  small 
holes.  Leave  the  ends  protruding  about  six  inches.  As  usual 
with  electrical  apparatus,  shellac  the  outside  layer. 

About  fifteen  hundred  ampere  turns  are  required  for  field 
excitation ;  the  particular  sizes  of  wire  will  depend  on  the  vol- 
tage of  the  armature. 

Fifty  volts.  Series:  five  pounds  of  No.  13  wire  (seventy- 
two  one-thousandths  inch  diameter)  wround  eleven  layers  deep. 


29 

Shunt :  three  pounds  of  No.  25  wire  (eighteen  one-thousandths 
inch  diameter)  wind  thirty-three  layers  deep.  For  a  compound 
field  use  first  two  and  one-fourth  pounds  of  No.  26  wire 
(sixteen  one-thousandths  inch  in  diameter)  twenty-nine  layers 
deep ;  wrap  on  a  few  turns  of  thin  paper,  shellac  discs  of 
paper  over  the  leading  ends  of  the  wrires  to  protect  their  insula- 
tion, and  wind,  in  the  same  direction,  one  and  one-half 
pounds  of  No.  14  wire  (sixty-four  one-thousandths  inch  in 
diameter)  three  layers  deep. 

Seven  volts.  A  series  field  is  unsuitable  for  plating.  For  shunt 
use  four  and  one-half  pounds  of  No.  17  wire  (forty-five  one 
thousandths  inch  in  diameter)  seventeen  layers  deep.  A  com- 
pound winding  may  have  in  the  shunt,  three  pounds  of  No.  18 
wire  (four  one-hundredths  inch  in  diameter)  fifteen  layers 
deep,  and  in  the  series  one  and  one-half  pounds  of  No.  6  wire 
(one  hundred  and  sixty-two  one-thousandths  inch  in  diameter) 
one  layer  deep. 

Twenty- five  volts.  Series  :  four  and  one-half  pounds  of  No. 
10  wire  (one  hundred  and  two  one-thousandths  inch  in  diameter) 
seven  layers  deep.  Shunt:  three  pounds  of  No.  22  wire 
(twenty-five  one-thousandths  inch  in  diameter)  twenty-three  layers 
deep.  Probably  the  builder  would  have  no  occasion  for  a 
compound  field  for  this  potential. 

One  hundred  and  ten  volts.  Series  :  four  and  one-half  pounds  of 
No.  17  wire  (forty-five  one-thousandths  inch  diameter)  seventeen  layers 
deep.  It  will  be  noticed  that  this  is  identical  with  the  shunt 
requirements  for  seven  volts.  Shunt :  three  pounds  of  No.  27 
wire  (fourteen  one-thousandths  inch  in  diameter)  forty-one  layers 
deep. 

In  each  case  an  odd  number  of  layers  has  been  stated  in  order 


to    bring    the   terminals    of    the    coils    at  opposite   ends  of  the  spool. 
Connections.       Any     kind     of     seasoned     hard    wood    is   suit- 


Shunt  Dynamo. 


SeriesDynamo. 


Shunt  Motor.       «3 


Series  Motor 


n 


QD 


Compound  Dynamo 


Rktosfat 


a  I   Series  Re versing  Mote 


FIGURE     15. 

able    for   the    connection   board.        Finish    it    in    varnish    or    shellac, 
and    drill    as    shown    in    Figure    14.       Rectangular   brass    strips    are 


to  be  drilled  and  tapped  8-32  and  attached  to  the  board  by 
screws  uf"  (Figure  4),  inserted  through  from  the  back  and 
entering  the  center  holes.  The  two  end  screws  for  each 
strip  "g"  (Figure  4)  enter  the  board  one-eighth  of  an  inch 
to  prevent  "  skewing."  These  holes  may  be  made  with  a  No. 
1 8  drill,  after  their  location  has  been  marked  from  the  strips.  Use 
no  shellac  on  the  surface  of  the  brass  as  electrical  contact 
would  thereby  be  destroyed.  Connections  are  made  by  soldering 
sheet  copper  clips  to  the  wires  and  clamping  them  to  the  blocks. 
Incandescent  lamp  cord  is  suitable  for  flexible  cables  to  connect 
the  brushes  with  the  terminals.  One  strand  will  be  sufficient 
for  the  current  of  a  fifty  or  one  hundred  and  ten  volt  armature, 
but  two  strands  for  the  twenty-five  volt,  and  four  for  the  seven 
volt  winding  should  be  used,  all  soldered  into  a  sufficiently  large  clip. 

By  means  of  this  simple  arrangement  of  contact  blocks, 
almost  any  combination  of  wires  may  be  made,  allowing  the 
machine  to  be  used  for  a  variety  of  purposes.  Figure  15  also 
shows  the  necessary  wiring  for  connecting  as  series,  shunt,  or 
compound  dynamo ;  series,  shunt,  or  reversing  motor.  It  is  not 
the  purpose  of  this  book  to  describe  switch-board  appliances, 
so  locations  only  of  rheostats  and  reversing  switch  are  shown. 

After  assembling  the  machine,  the  field  wires  should  be 
straightened,  and  short  pieces  of  small  soft  rubber  tubing  slipped 
on,  so  as  to  insure  insulation  from  the  frame. 

Testing  and  Using.  The  various  uses  to  which  the 
machine  is  put,  and  conditions  under  which  it  works,  will  de- 
termine just  which  of  the  connection  board  arrangements  to 
adopt. 

If  used  as  a  dynamo  to  run  incandescent  lamps  or  a 
plating  bath, — the  potential  controlled  by  a  rheostat  in  the  field, — 


32 

use  the  "Shunt  Dynamo"  board,  or  if  fairly  close  automatic 
regulation  is  desired,  use  the  "compound"  connections.  A 
rheostat  in  the  shunt  circuit  will  still  be  useful  to  compensate 
for  variations  in  speed.  When  no  rheostat  is  wanted,  connect 
its  two  points  on  the  board  with  a  short  wire. 

In  starting  a  shunt  or  compound  dynamo,  turn  the  rheostat 
until  all  the  resistance  is  "  out,"  that  is  equivalent  to  dispensing 
with  its  use.  Let  the  main  switch  controlling  the  lamp  circuit 
be  "  open."  Drive  the  armature  at  its  correct  speed,  2600 
revolutions  per  minute.  Set  the  brushes  on  the  "neutral' 
point, — that  is,  on  segments  which  connect  with  coils  just  half 
way  between  the  two  pole  pieces.  The  correct  location  is 
shown  in  Fig.  i.  Let  the  brushes  bear  with  a  firm  yet  even 
pressure ;  lift  one  of  them  from  the  commutator  and  touch 
wires  leading  from  a  battery,  or  other  source  of  continuous  cur- 
rent, to  the  field  terminals.  This  is  to  put  some  initial  magne- 
tism into  the  iron.  Remove  the  battery  wires  and  replace  the 
brush.  Move  the  yoke  slowly  back  and  forth ;  if  current  is 
being  generated,  sparks  will  appear  at  the  brushes,  and  strong 
magnetism  be  felt  at  the  poles.  For  use,  keep  the  brushes  on 
the  neutral  point,  which  is  the  position  of  least  sparking,  in- 
deed there  may  be  an  entire  absence  of  that  evil.  If  no  cur- 
rent is  generated,  remove  the  screws  holding  the  cable  termi- 
nals and  exchange  their  location  by  connecting  the  long  one 
where  the  short  one  was.  The  dynamo  should  now  generate. 
Always  allow  a  few  minutes  for  the  machine  to  "build  up,"  so 
called.  A  shunt  dynamo  is  often  very  sluggish  in  starting.  Now 
connect  the  lamps  by  closing  the  main  switch,  turning  the  rheo- 
stat if  necessary  to  adjust  the  potential.  Safety  fuses  of  stand- 
ard make  should  be  used  as  shown.  In  case  of  overload,  or 


33 

accidental     short-circuit,     the     fuses    melt     and     save     the     armature 
from  "  burn  out." 

For  starting  a  compound  dynamo, — the  same  method  may 
be  used,  with  the  additional  precaution  to  observe  that  the  cur- 
rent in  the  series  coil  must  be  in  the  same  direction  as  in  the 
shunt ;  otherwise  its  influence  would  be  to  oppose  instead  of 
help  the  regulation. 

A  series  dynamo  is  suitable  for  running  an  arc  lamp, — in 
this  case  a  small  one, — and  for  general  experimenting.  Adjust  the 
brushes  and  connect  a  battery  to  the  line  terminals.  The  arma- 
ture will  try  to  run  as  a  motor ;  if  it  tries  to  turn  against  its 
biushes,  remove  the  battery  wires,  connect  the  line,  and  drive 
the  armature  in  the  direction  of  its  brushes ;  the  dynamo  should 
now  generate.  If,  when  the  battery  is  connected,  the  arma- 
ture turns  with  the  brushes  (in  the  direction  in  which  they 
point),  reverse  the  cables  leading  from  the  brush  holders. 
Driven  in  its  proper  direction  again,  the  armature  should  gen- 
erate. 

Three  cases  as  a  mctor  need  to  be  considered.  If  uni- 
form speed  is  desired,  independent  of  the  load,  a  shunt  field 
should  be  used.  If  current  is  supplied  from  a  constant  poten- 
tial circuit,  a  rheostat  must  be  connected  in  the  armature  cir- 
cuit to  prevent  an  over-current.  Turning  the  main  switch  will 
allow  the  fields  to  get  magnetised,  but  the  armature  current  has 
to  travel  through  the  rheostat.  As  the  speed  increases,  turn  the 
resistance  out.  If  the  armature  tries  to  run  in  the  wrong  direc- 
tion, reverse  the  brush  holder  cables.  If  primary  batteries  are 
the  source  of  current,  the  gradual  lowering  of  the  zincs  into  the 
acid  will  obviate  the  necessity  of  a  starting  rheostat. 

For    variable    speeds    a     series    motor     is     required ;    a    rheostat 


34 

will  still  be  necessary  for  use  on  constant  potential  mains.  A 
series  motor  will  always  run  at  a  constant  speed  if  the  load  is 
constant ;  hence  it  is  common  to  put  series  windings  on  fan 
motors  because  of  cheapness.  If  used  to  drive  a  fan  a  collar 
should  be  put  on  the  pulley  end  of  the  shaft  to  run  against 
the  lining  and  receive  the  u  end  thrust,"  the  regular  shoulders 
being  insufficient  for  so  much  pressure. 

Besides  the  ability  to  run  at  various  speeds,  a  "reversible" 
motor  is  sometimes  desired.  One  line  wire  (Fig.  15)  leads  to 
the  connection  board,  the  other  to  the  reversing  switch,  which 
is  shown  in  diagram.  The  circuits  are  such  that  the  fields 
are  always  magnetised  with  the  same  polarity,  but  the  direction 
of  the  current  through  the  armature  is  reversible  by  moving  the 
two  parallel  fingers  of  the  switch.  The  reversal  of  a  motor  is 
accomplished  by  changing  the  current  through  either  field  or 
armature, — not  through  both.  A  starting  rheostat  is  also  in- 
cluded in  circuit ;  one  of  the  fuses  is  omitted  in  order  to  make 
the  connections  more  convenient. 

Regular  sizes  of  fuses  should  be,  — for  the  one  hundred  and 
ten  volt  winding,  three  amperes;  this  is  the  smallest  size  made. 
For  fifty  volts,  four  amperes ;  for  twenty-five  volts,  eight  am- 
peres ;  and  for  seven  volts,  thirty  amperes  capacity. 

If  the  builder  has  followed  the  directions  carefully  the 
machine  will  work  to  perfection, — it  cannot  help  it.  This  dy- 
namo is  suitable  for  a  variety  of  practical  uses,  not  the  least  of 
which  may  be  as  "exciter"  for  the  fields  of  a  small  alternator. 
As  a  motor,  it  will  run  a  fan,  several  sewing  machines,  or 
small  lathe.  With  success  assured  from  the  small  outlay  thus 
required  the  builder  may  properly  attempt  the  construction  of 
larger  machines. 


COMPLETE    SET    OF 

CASTINGS 

FOR     THIS     1-4    HORSE     POWER 

MOTOR  OR  DYNHMO 

With  book  giving  working  drawings  and 
directions  for  building  the  Dynamo  or 
Motor.  ------------ 


PRICE,  $3.75. 


Shaft  Stock,    15   cents. 


Screws,  40  cents. 


PRICES  OF  WIRE,  PER  POUND. 


NO. 

COTTON    WOUND 

NO. 

COTTON    WOUND 

SINGLE 

DOUBLE 

SINGLE 

DOUBLE 

11 

$    .35 

$    .37 

24 

$     90 

$1.14 

12 

.35 

.37 

25 

1.00 

1.27 

13 

.36 

.39 

26 

1.10 

1.38 

14 

.36 

.39 

27 

1.25 

1.57 

15 

.37 

.40 

28 

1.35 

1.69 

16 

.37 

.40 

29 

1.50 

1.89 

17 

.38 

.42 

30 

1.65 

2.07 

18 

.38 

.42 

31 

1.80 

2.23 

19 

.39 

.43 

32 

1.95 

2.28 

20 

.60 

.74 

33 

2.40 

2.85 

21 

.70 

.88 

34 

2.85 

3.42 

22 

.76 

.95 

35 

3.25 

3.88 

23 

.83 

1.05 

36 

4.37 

493 

Express  to  be  paid  by  purchaser.      Send  money  by  P.  O. 

order,   bank    check    or    registered    letter. 

Postage  stamps  not  received. 

BUBIER  PUBLISHING  CO., 

P.  O.   Box  3O9,   Lynn,   Mass. 


Note.      Be  sure  when  ordering  these  castings  to  state  that  you  want 
the   No.    2   Motor  or   Dynamo. 


HERE  IS  A  BOOK  WHICH  EVERYBODY  NEEDS. 


HOW    TO    BTTIZiD 

DYNAMO  -  ELECTRIC  MACHINERY. 

Bv     EDWARD     TREVERT. 

3flO   octavo  pages    of  working   drawings,    w*ood    cuts,   half-tone  illustrations   and 
practical   information    about   dynamos    and   motors. 


CHAPTER    1. 
2 

3. 

4. 

5. 

6. 

7. 

.8. 

9. 
10. 
11. 
12. 
13. 
14. 
15. 
16. 
17. 
APPENDIX  A 

B 

C 


OOKTTENTS. 

Historical  Notes. 

Principles  of  Dynamo-Electric  Machines. 
Methods  of  Field  Magnet  Winding. 
Forms  of  Field  Magnets. 
Armatures. 

How  to  Make  a  Toy  Electric  Motor. 
How  to  Make  a  Small  Dynamo. 
How  to  Build  a  Two-Light  Dynamo. 

How  to  Build  a  one  half  Horse  Power  Motor  or  Dynamo. 
How  to  Build  a  One  Horse  Power  Motor  or  Dynamo. 
How  to  Build  a  Twenty-light  Dynamo. 

How  to  Build  an  Alternating  Current  Dynamo  or  Motor. 
Types  of  Commercial  Dynamos.     (Direct  Current.) 
Types  of  Commercial  Dynamos.     (Alternating  Current.) 
Types  of  Commercial  Stationary  Motors. 
Types  of  Commercial  Railway  Motors. 
Management  of  Dynamos  and  Motors. 
Tables  of  Wire  Gauges. 

Some  Practical  Directions  for  Armature  Winding. 
Some  Practical  Directions  for  Field  Magnet  Winding. 


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